Remove node's name reference when the interface is detached;

otherwise, the ng_ether.ko KLD will never be unloadable after
all Ethernet interfaces are detached, as it should be, because
of the lingering extra reference.

Submitted by:	"Yevmenkin, Maksim N, CSCIO" <myevmenkin@att.com>

sys/netgraph/ng_ether.c

@@ -288,6 +288,7 @@ ng_ether_detach(struct ifnet *ifp)
 		return;
 	ng_rmnode(node);		/* break all links to other nodes */
 	node->flags |= NG_INVALID;
+	ng_unname(node);		/* free name (and its reference) */
 	IFP2NG(ifp) = NULL;		/* detach node from interface */
 	priv = node->private;		/* free node private info */
 	bzero(priv, sizeof(*priv));